Diversity and functional plasticity of root-associated fungi of Pinus massoniana in bauxite mine restoration areas.

Ectomycorrhizal fungi (EMF) play a key role in plant establishment and stress tolerance, yet their diversity and functional roles in mining restoration systems remain insufficiently resolved. In the present study, we investigated the culturable fungal community associated with ectomycorrhizal root tips of Pinus massoniana in bauxite rehabilitation areas, with particular attention to their symbiotic capacity and ecological roles. Fungi were isolated from root tips and sporocarps, identified using ITS sequencing, and evaluated through seedling inoculation experiments. A total of 25 operational taxonomic units (OTUs) were recovered from root-tip isolates, representing Ascomycota, Basidiomycota, and Mucoromycota. Several classical ectomycorrhizal taxa, including Suillus luteus, S. bovinus, and Phlebopus portentosus, formed typical ectomycorrhizal structures with P. massoniana. In addition, fungi not traditionally regarded as ectomycorrhizal, such as Schizophyllum commune, were able to form ectomycorrhizal-like associations. Other isolates, including Epicoccum nigrum, Trametes versicolor, and Morchella sp., colonized roots through dark septate hyphae and microsclerotia, indicating alternative interaction strategies. These results support the view that root-associated fungi in stressed environments encompass a continuum of ecological roles rather than discrete functional categories. The ability of some taxa to adopt multiple interaction modes suggests a degree of ecological plasticity that may be important for host adaptation in disturbed habitats. From an applied perspective, the identification of stress-tolerant EMF and facultative fungi highlights their potential use in the restoration of degraded mining ecosystems. Further work is needed to clarify the mechanisms underlying these interactions and their persistence under field conditions.